Paper-pulp digester



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C. CURTIS 8v N. M. JONES.

PAPER PULP DIGESTER.

Patented Nov. 8, 1892.

- C/arzwcwtid gmmtow To all whom t may concern:

ofl Bangor,

IO ing wood chips in the manufacture 'ofpaperpulp,

UNITED 'STATES erica.,

CHARLES cpnjris, oilT NEWTON, iiiissiicnosnfr'rs,faire riifriialvini, M;

' JOES, OF BA 'Pansements messias,

SPECFvICATION forming pait of Lettersatent No. 44353123, dated November S, 1892. 4 ippiicaiion tied september ze, 1892. seni no. atenei. v ci@ einem Be, it known that We, CHARLES CURTIS, of

` Newton, in the county of Middlesex and State Massachusetts, and NATHAMEL M. JONES,

' in the county of Penobscot and State of Maine, have invented certain new and useful Improvements inPape'r-Piilp Div gesters, of which the following is a specifica` 'til-)nt This invention 'relates to digeste'rs for cookand` has for its object to provide such a construction Aas will protect the metal shell of the digester against the acid solutions eniployed to dissolve theresins andlguinsotthe v Wood.

' To these ends the invention consists, mainly, vvin a digester comprising an external shell or vcasing of lmetal and a lining 'composed of zoV compressed carbonized cement or artificial' f f .less extent if the blocks were simply fOI'med stone.

Of theacconipanying. drawings,.ferming' a part of this specification, a vertical section of a digester embodying our z5 invention, the central portion being broken away. represents a perspective view of one of the blocks.

. The same letters ofA reference indicate theV rsame parts in both the igures.

,o In the drawings, ct represents the vshell of y the digester, which is preferahlyof cylindrical form and composed of anysuitable metal, such as iron, steel, phosphor-bronze, brass, te.

b represents an intermediate lining, which 5 is preferably composed of asbestus and. cement made into a plastic composition and applied to the inner surface of the shell in a plastic state, its object beingto protect the inner cement lining hereinafter described and to prevent contact of the acid solution with the metalshell in the event 'of leakagev through the cement lining.

@represents the Vcement; lining, which 'is composed, preferably, of Portland cement and ground glass or quartz, with or withonta per- XVe do not limit intoan artiiicial stone and rendered extremely Figure l represents .hard and durable, so that itis particularly adapted foriise as a digester lining, it being imperviousl to the acid and comparatively free from liability te crack and chip.

We show `the cement lining as constructed in sections 8 8, .which are provided at their edges with tongues 9 and 'recesses 10, the tongues of each section entering the recesses of the adjacent section, so that the sections are formed in suitable iiasks or amolds, the ingredients of the cement vbeing inserted in .the molds and subjected to sniiicient pressure therein before the setting of the cement to ina-ke the blocks uniformly denseaiid free from pores or air-holes. The compression of the cement is an important partof'oliriii# vention and prevents liability oi' the acid solutionfworking its Way through the blocks, which liability would exist to a greater or without compression. i

It will he seenfthatth'e lining of caibonized cement, being extremely hard and dense, is well adapted not only to -resist the acid solution, but' also the heat which is used in cooking the Wood chips, preventing both the acid and the heat from reaching the shell of the ldigester, while the intermediate lining b constitutes a safeguard or protection forV the metalI shell against the action cf the acid sooverlap at their joints. The sections or blocks vliition in the event of cracking ofthe cement.

'We do not claim, broadly, the process of carhonizing cement by subjecting the same to carbonio-acid gas; but We are the first, so far as we are aware, to provide a metal shell with a lining of carbonized cement.

vWe do not limit ourselves in all cases to the usecfthe intermediate lining o, and may place the cement lining directly against the inner `surface of the metal shell, or may interpose between. the inner cement lining and shell only av coating` of eeinent.-

We are aware that digester-shells have heen lined'with glazed or vitrilied tiles and with porcelain tiles; but we malte the following Ybroad distinctions between a carbonized-ce. ment lining and a liningot glazed or vitrified .IOO land has substantiallyf.

and porcelain tiles, viz: First, carbonized cement is 'homogeneous the saine coefficient of expansion and con; f

ressive :strainV on the-lining. Onltheother a meotis' moregelasiic'thnn glazedlo'rvtrie'gi diers'from ourfliningiu thatjt is. much more -i rittle and livlble. to crack 'and chip olf. -An f '(ibjection,y to a -contiuuouscement linlg pmake theliningoff uniform den'sity. -IIence ils Iible'tobe permeaiied by theacid. Our ningis., made of previoilsly-molded blocks,

ioing,aud thusv exerting an injurious.com -r and', a lining of -glazed orvtriiied-tile or' of porcelain tile lwill'' conlmrzt more slowly than Y the metal shell, so that there wouldbe apress- 'me o n the lini-ng'tendiog to crack and 'chip' fa llsticst'ate to the 'interimof the', shelLfl Y :ich llningha's never b eu-mirbonize'd, hoivf' e v er, priormyour'in-ven,tion,yand therefore" vcemengasset forth. v -f @In testimony whereotwe -have =sig'ned our names to this speciiicatiori,in the. 'pregece of two 'suhscribingwvitnesseg this 8th day of Sepemher,' A-.D. 1892.

itis often defectivel'y porousl insp'ots, and

.-hgmateiiolof'whichiseiibjectedto'preseure ci'il'ijixi-g'z-l molilig'uooerfion, thizisihere I Ais nodimcultyiomaking' -ali-the-blocks'of "uniform denity', mdf strength; -thev inherent strength of the liucread by arbonizamn' v The'. advantages-due. to the compression ,of 3s ,the @dmanr-are no t whollydependentn the,

crboniziion' of thec'ement, althoughihelat" ter is'ave'r'yimportent fea`ture.We theref fore desire to cover a' lining of .eompresed 14 l1 The improved pulp-digester -herendescribe compriein'gin Reconstruction; metal shell` and af lining 'composed of compressed 'carbonize'dfcemen as setforthf f2. The improved p lp-digesterflierei de-4 f scribed, comprisingin'its construction' a metal shell and' 'a` lining-composed of' compresse dl 

